Wood coloring process



Patented June 16, 1%31 WWW FATE OFFICE CHARLES E. LENTZ, OF SOUTH BEND, INDIANA, ASSIGNOR TO THE SINGER MANUFAC- TUBING COMPANY, OF ELIZABETH, NEXV JERSEY, A CORPORATION OF NEW JERSEY WOOD COLORING PROCESS No Drawing.

This invention relates to a process of coloring Wood by impregnation and has for its object to obtain a uniformity of coloring of Wood under conditions avoiding delete- 5 rious effects upon the wood.

The present process is more particularly adapted for coloring lumber and veneers throughout the thickness thereof, whereby relatively inexpensive wood such as, for instance, yellow birch may be caused to resemble walnut.

This wood coloring process, in general consists in vacuating the pores and interstices of the wood, thereby rendering the Wood absorbent, subjecting the vacuated wood to the wood may be piled solid in slightly separated tiers. After being loaded, the receptacle is closed to make it air and liquid tight and connections are opened to a suitable air-exhausting apparatus which is thereupon operated to create within the receptacle a vacuum of preferably slightly over 26.. This vacuum is maintained for a period of approximately two hours to vacuate the pores and interstices of the wood thereby rendering the wood ab sorbent.

At the end of the vacuum period, the airexhausting apparatus isdis'connected from the receptacle, and while the cylinder is still under vacuum a measured quantity of ammonia gas is blown into the receptacle by opening suitable connections with containers of anhydrous ammonia. It has been determined by experimentation that a desirable quantity of ammonia gas introduced into the receptacle is approximately 25 lbs. for each Application filed October 20, 1928. Serial No. 313,949.

1,000 board feet of lumber to be colored, particularly' when coloring yellow birch to resemble walnut. It is to be understood that while the ammonia gas is blown into the receptacle under the pressure of the anhydrous ammonia within its containers, the quantity introduced creates only a negligible pressure Within the receptacle.

After the desired quantity of ammoniagas has been introduced into the receptacle, the connections With said ammonia containers are shut 01? and steam is then rapidly intro duced into the receptacle through suitable connections and preferably of sufl icient quantity to raise the temperature within the receptacle to approximtely 235 F., the pressure within the receptacle reaching approximately 8 lbs. gauge, i. e., substantially the pressure of confined saturated steam at said temperature. When the desired temperature is attained within the receptacle, the flow of the steam is partly shut off or otherwise regulated to insure the continued introduction into the receptacle of only enough steam to maintain the temperature at 235 F. for a period which is preferably approximately twelve hours. During the described heatmair tenance period, a substantial portion of the steam becomes condensed, the condensation collecting about the heating coils before mentioned.

In order to equalize the temperature in the receptacle during this. twelve hour period, steam or some other suitable heating medium is for the first time passed into the heating coils at the bottom of the receptacle. These heating coils have no openings to permit of entrance directly'into the receptacle of the heating medium introduced into the coils, said heating medium during the referred to twelve hour period being only sufficient to provide for temperature equalization within the receptacle.

At the end of said twelve hour period the introduction of steam directly into the re; ceptacle is discontinued and the heating medium introduced into the coils is increased to generate sufficient heat to cause revapori- 'zation of the condensation which hascollected about the coils. By this means alone,

the desired temperature of a proximately 235 F. is continued for a furt er period of preferably approximately thirty-six hours.

The end of sad thirty-six hour period completes'the wo coloring process, whereupon all steam is shut oil any pressure in the rer ceptacle is relieved by blowing off the vapor extended beyond thesteam introduction period,vprovides for a thorough diflusion of the ammonia in the wood pores and interstices, thereby causing an unusual dc ee of uniformity of coloring and this wit out any dapparent deleterious efiects upon the woo Having thus set forth the nature of the invention, What I claim herein is 1. The process of coloring wood, consisting in vacuating the ores and interstices of the wood thereby ren ering the wood absorbent, introducing a measured quantity of anhydrous ammonia into a closed receptacle containing the wood, and then introducing steam into said receptacle to raise and mainitam for a. definite period a temperature of approximately 235 F.

2. The process of coloring wood; consistmg in vacuating the ores and interstices of the wood thereby ren ering th e wood absorbent introducing a measured quantity of anhydrous ammoniainto a closed receptacle containing the vacuated wood, introducing steam rapidly into said receptacle to raise the temperature to a predetermined degree, and then introducing steam more slowly thereby maintaining the predetermined degree of temperature for a definite period, I

3. The process of coloring'wood consisting in the successive steps comprising vacuating the pores and interstices of the wood thereby rendering; the wood absorbent, introducing a measure quantity of anhydrous ammonia into a closed receptacle containing the wood,

introducing steam into the receptacle ior a definite period, and then revaporizing for a definite period steam' condensation within the receptacle.

4. The process of coloring wood,'consisting in subjecting the wood to a vacuum process in a closed receptacle, introducing a measured quantity of an ydrous ammonia into the re- 5 ceptacle, and subjecting the receptacle contents to steam to maintain a substantially constant temperature of approximately 235 F.

' for a definite period.

5. The rocess of coloring lumber, consisting in sub ecting the lumber to a vacuum process in a closed receptacle, introducing into a receptacle approximately 25 lbs. of anhydrous ammonia per 1,000 board feet of lumber within the receptacle, and heating the receptacle contents by steam for a definite period with an incidental pressure of approximately 8 lbs. v

e. 6. In a process of coloring wood, that step which consists in subjecting wood and anhydrous ammonia contained 1n a closed receptacle to steam to maintain a temperature of approximately 235 F. for a definite period. 7. The process'of coloring wood in a closed receptacle, consisting in introducing anhydrous ammonia intothe receptacle, heating the receptacle contents by introducing steam into the receptacle under conditions resulting in a partial condensation of the steam, and then continuing heating the receptacle contents by revaporization within the regang ceptacle of the condensed steam.

8. The process of coloring wood in a closed receptacle, consisting in introducing anhydrous ammonia into the receptacle, introducing steam directly into said receptacle to raise and maintain a predetermined temperature for a definite period, then interrupting the introduction of steam directly into the receptacle and continuing the maintenance of the previously attained temperature for a further definite period.

In testimony whereof,'I have signed my name to this specification. CHARLES E. LENTZ. 

